Regarding the valve adjustment, I'm assuming Stihl considers that a dealer only adjustment. I didn't see the procedure in the operators manual.

The valves being out of adjustment often cause problems like hard starting and slow to rev. I adjust mine once a year whether I have a symptom or not. Usually one or both valves need a small adjustment. I just did 2 4 Mix engine valve adjustments this past Sunday and it took about 45 minutes total for both of them. The adjustment is super easy and the only special tool you need is the special feeler gauge that you can buy from your dealer. Here's a video from Stihl that shows how to do it.